Nested Planetary Gear Hybrid Drivetrain for Compact Axial Length
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Solution Overview
Problem
Existing power-split hybrid drivetrains in hybrid vehicles face challenges in achieving improved drivability, fuel economy, and towing capacity without significantly increasing the length of the power-split device, which is often addressed by adding additional planetary gear sets that complicate the design.
Innovation Solution
The implementation of a hybrid drive train with a nested power-split planetary gear set and selectable one-way clutches that allow for multiple operating modes, including the use of a common carrier and one or more clutches or brakes, enabling enhanced power driving modes without increasing the axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional planetary gear sets are added to improve drivability, fuel economy, and towing capacity, then the system performance is improved, but the axial length of the power-split device increases
Solution Approach 1:
The patent implements a nested planetary gear configuration where an inner planetary gear set is positioned within an outer planetary gear set, sharing a common carrier. This nesting arrangement allows multiple gear functions to be achieved within a compact axial space, providing multiple operating modes for improved drivability, fuel economy, and towing capacity without significantly increasing the axial length of the power-split device.
2Adaptability or versatility
If additional planetary gear sets are added to provide multiple operating modes, then the system versatility is improved, but the device complexity increases
Solution Approach 1:
The patent merges two planetary gear sets into a single integrated unit with a common carrier, where the inner and outer planetary gears share the same carrier structure. This consolidation reduces the number of separate components and simplifies the overall device architecture while still enabling multiple operating modes through selective engagement of different gear elements.
Solution Approach 2:
The common carrier serves multiple functions by supporting both the inner and outer planetary gear sets, allowing a single structural element to perform multiple roles in power transmission. This multi-functionality reduces the need for additional separate components, thereby decreasing device complexity while maintaining versatility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration provides improved drivability, fuel economy, and towing capacity while maintaining the original length of the power-split device, reducing energy losses at highway speeds and offering additional driving modes.
Implementation Method 1
a friction lining is pressed against a rotating drum by a movable piston... the friction lining is pressed against the drum with a force sufficient to lock the drum against rotation in the forward direction
Implementation Method 2
a drum-piston mechanism is provided in which a friction lining is pressed against a rotating drum by a movable piston
Data Source
AI summary
A hybrid drive train includes a first electric motor, a nested power splitting planetary gear set having a first carrier element and a second carrier element, an inner sun gear coupled with the first electric motor and an outer sun gear coupled with an output shaft. A first selectable one-way clutch controls the first and the second carrier element, and switches between operation as a one way clutch and operation as a brake. A second selectable one-way clutch controls a ring gear of the nested planetary gear set, and switches between operation as a one way clutch and operation as a brake. The extra outer planetary gear set improves lowing capacity at higher speeds without substantially increasing the axial length of the power split device.